I get asked this question a lot, both in the office and with the wrestling team that I coach. The question is usually brought on by a concerned parent who is looking for answers because their adolescent athlete is looking to begin training, or often times the parent asking the question is hoping to start prepping their 7 year old superstar for the NFL combine. Either way, I will address my (humble) views and opinions on the issue.
First, YES it is safe (if done right). The American Academy of Pediatrics agrees with me here.
Second, NO it will not harm growth plates or stunt growth (again, if done correctly).
Third, weight training is incredibly beneficial for kids in the class room as well as the competition field.
Fourth, yes I have seen many many kids compete in the sport of weightlifting. No, this article is not talking about them. This article is geared towards the average person with the average adolescent athlete. For the weightlifters out there reading this, know that this article is geared towards the person who cant differentiate a bicep curl from a clean and jerk. I know from having spent enough time around strength sports that the kids who compete in them are coached very very well and many of them have far better technique and progression than their adult counter parts. If you leave a comment on this article of a video of a kid from another country squatting 200 KG, I will simply cut and paste this last paragraph under your comment.
I will not address the safety and growth plate issues any further in this post because both topics have been written on ad nauseam and there is nothing I can add to that particular conversation. I will emphasize on the "done correctly" part in a moment.
Rather than looking for some magical age where it is all the sudden safe and effective for a child or adolescent to begin strength training, my personal opinion is that we ought to determine relevance of strength training based on relevance of other strength and developmental baselines.
Here is an example. Back when I was involved in CrossFit Mokena, we routinely had high school aged kids come in to try CrossFit out. Many of these kids were athletes, and while it may seem like I am poking fun at these kids, I assure you I am not. I highlight these kids as examples because they remind me of myself at that age. Eager to train, eager to learn, eager to get stronger and faster. The vast majority of times the kids would come into the gym and tout the numbers they put up in their high school weight rooms. I can't tell you how many times I would hear from sophomores or juniors that they were back squatting 400+ pounds (read: quarter squatting), or bench pressing near 300 pounds. When we would introduce them to simple bodyweight movements, however, such as an air squat or a pushup or even a simple plank, their form would break down within a matter of only a few repetitions. I recall one particular encounter with a father who insisted his kid (15 years old) could bench press 270 pounds and that I should allow him to get into the advanced classes with the advanced crossfitters. I informed the father that would not be happening until I witnessed the young man string together 20 consecutive push ups with good form, something I hadn't seen him to thus far. In fact, if memory serves, he could not string more than 8-10 pushups together, and the ones he did complete were not a full range of motion and had excessive sagging in the middle of his body demonstrating a very weak core.
They left and found another gym that was less responsible.
Again, it may sound like I'm poking a little fun, but I assure you I'm not. Stories like this highlight where my opinion on this topic stems from. I personally believe that adolescents should begin adding resistance training AFTER AND ONLY AFTER they have demonstrated core competency in basic body weight movements. Athletes should be spending their early developmental years mastering simple unloaded body weight movements such as:
-Bulgarian split squats
-Pull up and chin up progressions
-Did I mention push ups?
These movements not only require muscular strength and endurance to do correctly, they also instill proficiency in different movement patterns. That proficiency and coordination is just as much neurological as anything else. It involves the nerves and muscles working together in synchronicity (neuromuscular junctions). Let's imagine a 10-13 year old athlete in our heads. Picture them playing their sport. Do you see a lot of kids in that age group displaying a particularly high amount of coordination yet? (mind you, the ones who have achieved high levels of coordination are typically the better athletes in middle school, but often times the rest of the kids catch up to them by senior year of high school and level the playing field a little bit). If an athlete is unable to demonstrate adequate levels of coordination in a body weight squat movement, why would we add a load to the movement and stress the athlete in an inefficient means?
Sadly, this is what happens all too often in middle school and high school. Kids start doing some relatively high levels of weight training before they are proficient with their own body weight which leads to form errors and inefficiencies that some day need to be corrected. (Don't get me started on the high schools that encourage kids to load the bar up only to do improper bench presses, squats etc, or even the high school sport coaches that allow that to happen). I personally believe that every middle school and high school that have sports which utilize the weight room, should have an assigned strength coach who works with all sports, teaching all athletes how to properly train and programming for them as such.
So what is the answer to the title of this article? When can kids start to lift? When your kid can string numerous pushups together going through a full range of motion without excessive sagging in the core then they are likely getting closer to being able to lift. When your kid can do body weight squats without coming up on their toes, letting the knees bow in, rounding their mid and low back out, and generally maintain a solid athletic posture, they are likely able to start squatting with a load. When the kid can lift a relatively heavy object off the ground without looking like a camel, they are likely ready to begin deadlifting. When the kid can hold a solid plank position for a minute (arbitrary number, but you get my point) they have developed good enough core strength to start lifting. Last but not least, when the kid has developed the maturity to maintain focus in a training environment, and the maturity to understand proper progression (the second one will likely require a good coach or trainer) then they are ready.
Was this answer not scientific enough? Is it too open to individual interpretation? Good. Thats what I wanted. There is no magic age and there is no magic "voila" moment to decide when the kid can start training heavy. The actual answer is very subjective. Kids mature physically and mentally at different rates. In the meantime, get your kid doing the body weight movements. They can practice the deadlift, squat, bench, and power clean with a PVC pipe but in the meantime, they should be able to show you the movements listed above. Don't put the cart before the horse.